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Physics > P1 - Energy > Flashcards

P1 - Energy Flashcards

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1
Q

What are all the energy stores?

A
  • Thermal
  • Kinetic
  • Gravitational Potential
  • Elastic Potential
  • Chemical
  • Magnetic
  • Electrostatic
  • Nuclear
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2
Q

What are the different ways in which energy is transferred?

A
  • Mechanically (by a force doing work).
  • Electrically (work done by moving charges).
  • Heating.
  • Radiation (light or sound).
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3
Q

What is a system?

A

A single object or a group of objects that you’re interested in.

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4
Q

What happens when a system changes?

A

Energy is transferred. It can be transferred into or away from the system, between objects in the system or between different types of energy stores.

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5
Q

What is a closed system?

A

Matter and energy cannot enter or leave. The net change in the total energy of a closed system is always zero.

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6
Q

What is work done?

A

Energy being transferred, e.g. a ball dropped from a height is accelerated by gravity, so the gravitational force does work.

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7
Q

What happens when the speed of an object changes?

A

Energy is transferred to the kinetic energy store if it speeds up, or it is transferred away from the kinetic energy store if it slows down.

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8
Q

What is the formula to calculate the kinetic energy?

A

Kinetic Energy = 1/2 X mass x velocity^2

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9
Q

What does lifting an object do?

A

Work is done on the object, causing a transfer of energy to the gravitational potential energy store. The higher the object is lifted, the more energy is transferred to this store.

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10
Q

What does the amount of energy in the gravitational potential story of an object depend on?

A

The mass, height and strength of the of the object.

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11
Q

What is the formula to calculate gravitational potential energy?

A

Gravitational Potential Energy = mass X gravitational field strength X height

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12
Q

How does air resistance affect a falling object?

A

When an object falls, its gravitational potential energy store transfers to jts kinetic energy store. Air resistance causes some energy to be transferred to other energy stores in the object or to its surroundings.

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13
Q

What does stretching and squashing an object do?

A

Transfer energy to its elastic potential energy store.

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14
Q

What is the formula to calculate elastic potential energy?

A

Elastic Potential Energy = 1/2 X spring constant X extension^2

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15
Q

What is specific heat capacity?

A

The amount of energy need to increase the temperature of 1kg of a substance by 1•C

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16
Q

What is the equation for specific heat capacity?

A

Change in thermal energy = mass X specific heat capacity X temperature change

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17
Q

Describe the specific heat capacity investigation.

A

1) Get a block of a material with two holes in it, one for the heater and one for the thermometer to go into.
2) Measure the mass of the block with a mass balance.
3) Wrap the block in an insulating later to reduce the energy transferred from the block to the surroundings.
4) Insert the thermometer and heater into the holes.
5) Measure the initial temperature of the block with the thermometer.
6) Set the potential difference on the power supply which is connected to the heater to 10 volts. Turn on the power supply and start a stopwatch.
7) When you turn the power on, the current in the circuit does work on the heater, transferring energy electrically from the power supply to the heater’s thermal energy store. This energy is then transferred to the material’s thermal energy story by heating, causing the temperature to rise.
8) As the block heats up, take readings of the temperature and current every minute for 10 minutes.
9) Turn off the power supply, then use the measurement of the current and potential difference to calculate the power supplied to the heater (P=IV).
10) Calculate how much energy has been transferred to the heater at the time of the each temperature reading using the equation E=PT.
11) Plot a graph of energy transferred to the thermal energy store of the lock against temperature.
12) Find the gradient of the straight part of the line.
13) Calculate the specific heat capacity using 1 / (gradient x mass of the block).

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18
Q

What is the conservation of energy?

A

Energy can be transferred, stored or dissipated, but can never be created or destroyed.

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19
Q

What is power?

A

The rate of energy transfer or the rate of doing work.

20
Q

What are the equations for power?

A
  • Power = energy transferred / time
  • Power = work done / time
21
Q

What is conduction?

A

Conduction is the process where vibrating particles transfer energy to neighbouring particles.

22
Q

How does conduction work?

A

When an object is heated, the energy transferred to its thermal store is shared across the kinetic energy stores of the particles in the object. The particles vibrate more and collide with each other, causing energy to be transferred along the object until it is transferred to the other side of the object.

23
Q

What is thermal conductivity?

A

A measure of how quickly energy is transferred through a material by conduction.

24
Q

What is convection?

A

Energetic particles move away from hotter to cooler regions.

25
Q

How does convection work?

A

When you heat a region of a gas or a liquid, the particles move faster and the space between individual particles increases. This causes the density to decrease in that region. Because they can flow, the warmer and less dense region will rise above denser, cooler regions.

26
Q

How do radiators create convection currents?

A
  • Energy is transferred from the radiator to the nearby air particles by conduction.
  • The air becomes warmer and less dense.
  • The warm air rises and is replaced by cooler air, which is then heated by the radiator.
  • At the same time, the heated air transfers energy to the surroundings, so it cools, becomes denser and sinks.
  • This cycle repeats, creating a convection current.
27
Q

How can we reduce unwanted energy transfers?

A
  • Lubrication.
  • Thermal insulation.
28
Q

How does lubrication reduce unwanted energy transfers?

A
  • When something moves, there is at least one frictional force acting against it such as air resistance.
  • This causes some energy in the system to dissipate.
  • Lubricants reduce the friction between the objects’ surfaces when they move.
  • They are normally liquids so they can flow easily between objects and coat them, such as oil.
29
Q

How can and does insulation reduce unwanted energy transfers?

A
  • Have thick walls that are made from a material with a low thermal conductivity. The thicker the walls and lower the thermal conductivity, the slower the rage of energy transfer will be.
  • Use thermal
30
Q

How do you investigate the insulating properties of a material?

A
  • Wrap 0 layers of the material around the metal can.
  • Pour water heated by a kettle in the metal can, using a measuring cylinder to measure the volume of water.
  • Measure the initial temperature with a digital thermometer.
  • Use a stopwatch to measure five minutes and then record the final temperature on the digital thermometer.
  • Calculate the temperature decrease.
  • Repeat these steps with either a different material or different amount of layers of a material.

Controlled Variables:
- Use the same initial temperature of water.
- Use the same volume of water.
- Use the same number of layers if investigating different materials.

31
Q

How do you calculate efficiency?

A

Useful Power Output
——————————
Total Power Input

32
Q

What is the difference between renewable and non-renewable energy?

A
  • Renewable energy resources will never run out.
  • Non-renewable energy sources will run out one day.
33
Q

What are the three main fossil fuels?

A

1) Coal.
2) Oil.
3) Natural gas.

34
Q

Give examples of renewable energy sources.

A
  • The Sun (Solar)
  • Wind
  • Water waves
  • Hydro-electricity
  • Bio-fuel
  • Tides
  • Geothermal
35
Q

What are the advantages and disadvantages to both renewable and non-renewable energy sources?

A

Renewable:
+ These will never run out.
+ They do less damage to the environment than fossil fuels.
- They don’t provide much energy.
- Some are unreliable as they depend on the weather.

Non-renewable:
+ They are reliable.
- They will all run out one day.
- They damage our environment.

36
Q

How are renewable and non-renewable energy sources used for transport?

A

Renewable:
- Vehicles un on pure bio-fuel or a mix of bio-fuel and petrol or diesel.

Non-renewable
- Petrol and diesel powered vehicles use fuel created from oil.
- Coal is used in some steam trains to boil water to produce steam.

37
Q

How are renewable and non-renewable energy sources used for heating?

A

Renewable:
- A geothermal heat pump uses geothermal energy resources to heat buildings.
- Solar water heaters work by using the sun to heat water which is then pumped into radiators in the building.
- Burning bio-fuel or using electricity generated from renewable resources can also be used for heating.

Non-renewable:
- Natural gas is the most widely used fuel heating homes in the UK. The gas is used to heat water, which is then pumped into radiators throughout the home.
- Coal is more common burnt in fireplaces.
- Electric heaters use electricity generated from non-renewable energy sources.

38
Q

How do wind turbines generate electricity?

A

Wind turbines are placed in exposed areas like moors or coasts where there are strong winds. Each turbine has a generator inside of it. The wind turns the turbine which turns the generator, converting kinetic energy into electrical energy which can be transported to the national grid.

39
Q

How do solar cells generate electricity?

A

They generate electrical currents directly from sunlight.

40
Q

Where do solar cells work best?

A
  • In low energy devices such as calculators and watches so they don’t need batteries.
  • In remote areas such as the Australian outback.
41
Q

What are the pros and cons of wind and solar energy?

A

Pros:
+ Low running costs.
+ Don’t produce pollutants, so there is no pollution.
+ Don’t damage the environment.
+ Cheaper every year.

Cons:
- High upfront/initial costs.
- Making wind turbines and solar cells produces pollutants.
- Unreliable as they are dependant on the weather.
- No way to increase supply in times of peak demand.
- Take up lots of space.
- Wind turbines are too noisy and don’t look nice (visual and noise pollution).

42
Q

How does geothermal power work?

A

It uses thermal energy generated and stored in the earth’s crust from the initial formation of the planet and radioactive decay of radioactive elements deep inside the Earth. It is possible in volcanic areas where hot rocks lie near the surface.

43
Q

What can geothermal energy be used for?

A
  • Directly for heat: Water is pumped into the ground and heated up. It is then pumped back up to the surface to heat homes. This is cheaper than generating electricity.
  • Generate electricity: Pump water to the ground until it is heated into steam. The steam turns the turbine which turns the generator, converting kinetic energy into electrical energy.
44
Q

What are the pros and cons of geothermal energy?

A

Pros:
+ Installing power plants only damages the environment slightly.
+ Running power plants doesn’t produce any pollutants.
+ Renewable.
+ Reliable over long periods.

Cons:
- Can only be used in certain areas such as volcanic regions.
- Power plants can be expensive to build.

45
Q

How does hydro-electric power generated?

A

A hydro-electric dam stops water flowing in a river, forming a reservoir. The difference in water levels on each side of the dam generates the electricity as it gives the water lots of gravitational potential energy. The force of the water being released from the reservoir behind the dam turns the turbines which turns the generators.

46
Q

How do tidal barrages work?

A

Tidal barrages are big dams built across river estuaries with turbines in them. As the tide comes in, it fills up the estuary. When the tide goes back out again, the force of the water turns the turbines which turns the generator. Tides are produced by the gravitational pull of the Sun and Moon.

47
Q

What are the pros and cons of hydro-electric dams and tidal barrages?

A

Pros:
+ Produce large amounts of energy with no pollution.
+ Reliable source of electricity.
+ Low running costs.
+ Work on both large and small scales.
+ Hydro-electric dams have immediate responses to increased demand.

Cons:
- Have a big impact on the surrounding environment.
- Initial set up is expensive.
- Hydro-electric dams can flood huge areas such as important habitats or even villages.

Physics (2 decks)

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